This is a term used to a being whos hands are clammy but no moisture. When clammy your hands tend to feel like a smooth rubbery surface. McStevens is used to indicate a name. Plus it has a nice sound to it. So when called Clammy McStevens let it be known your hands are clammy. Remember this is not like Shlaggin Shaginsins Disease. because thats when there is exsesive amounts of moisture and sweating perfusely of the palms. Don't get the two confused.